For any human subject, his (or her) point-of-gaze can be defined as that single point in the surrounding space which is the instantaneous object of his visual regard. Research proposed by this application will provide quantitative evidence that a subject's point-of-gaze can be iteratively measured and monitored by specific algorithms operating on a sequence of digitized video images captured at standard video rates. The algorithms and underlying methodology are relatively simple, relying upon basic trigonometric and geometric functions to execute the necessary calculations. Long term objectives Include the development of an inexpensive computer mouse emulator specifically designed to provide significant improvements in precision and ease-of-use (over the current state-of-the-art), promising an instrumentation breakthrough in visually mediated cognition research. Program descriptions and research topics listed in PHS 94-3 to which the proposed research directly applies include: 4.A (NIA); 27.D.1, 27.1).5, 28.A, and 28.E (NICHD); 106.C (NINDS). Others for which this technology may find ready application include: 91.G.4 (NIMH); 113.C, 116.B, 116.D (NCRR). Lastly, this research inherently fits the institutional mission of the NEI. PROPOSED COMMERCIAL APPLICATION: This research validates a methodology - a technology - which will find application in man/machine interfaces for the disabled, cognition research, human factors research and monitoring, virtual reality environment enhancement, and operator safety monitors for trucks, trail~s, planes, and nuclear power plants.